Field of the Invention
Embodiments of the invention generally relate to a permanently or temporarily implantable medical device including an elongate electrical conductor.
Description of the Related Art
Implantable medical devices, for example electrode lines for electrostimulation, have the disadvantage that their electrical conductor heats up in an electromagnetic alternating field, for example in an MRI scanner, because electromagnetic alternating fields induce electrical currents in the electrical conductor.
Specifically, at least one stimulation electrode line is typically connected to implantable cardiac pacemakers or defibrillators. At a proximal end of the line, which is intended for connection to the cardiac pacemaker or defibrillator, there is generally a standardized electrical terminal, and at a distal end of the line, which is intended for placement in the heart, there is generally one or more electrode poles. Typically, an electrode pole is used to deliver electrical pulses, for example to the tissue (myocardium) of the heart or to sense electrical fields in order to sense activity, for example cardiac activity, within the scope of what is known as “sensing”.
For this purpose, two electrode poles typically form electrically conductive surface portions of an electrode line. The electrode poles are typically provided as ring electrodes in the form of a ring around the electrode line or in the form of a point electrode or tip electrode at the distal end of the electrode line.
The electrode poles are electrically conductively connected, via one or more electrical conductors, to contacts of the electrical terminal of the electrode line at the proximal end thereof. One or more electrical conductors, which electrically connect one or more of the electrode poles to one or more contacts, thus run between the contacts of the electrical terminal of the electrode lines, at the proximal end thereof, and the electrode poles at the distal end of the electrode line. These electrical conductors are be used for transmission of stimulation pulses to the electrode poles and/or for transmission of electrical signals, received by means of the electrode poles, to the proximal end of the electrode line. The electrical conductors are also referred to herein as functional conductors.
Generally, another disadvantage of typical implantable medical devices include the use of filter elements integrated into the electrode body. The electrode line structure is thus weakened in terms of the electrode line physiological properties, wherein the electrode line is larger and more rigid, such that the risk of tissue irritation and perforation increases. In addition, typically, the filter elements are located in the therapeutic path. As such, generally, the longevity of the structure or construction is thus jeopardized or restricted. Band-stop filters, which are typically used, are frequency selective.
Generally, functional conductors are electrical conductors necessary for the functions of the respective electrode line and, as such, are typically exposed to the risk that electrical currents will be induced in them as a result of external alternating magnetic fields. Typically, this may lead to an undesired heating of the functional conductors or of the electrode poles connected thereto, or may lead to delivery of corresponding currents via the electrode poles to surrounding tissue and therefore heating of the surrounding tissue.
As such, in view of the above, there is a need for a medical device, such as an electrode line, that is impaired as little as possible by electromagnetic alternating fields. In addition, there is a need for an implantable medical device wherein heating of an electrode line or of a catheter in an MRI scanner is reduced.